"Porter changed several times during its history. From a 100% brown malt beer to one brewed from a mix of brown and pale malts. With the introduction of black malt in 1817, it was possible to drop brown malt altogether. Though most London brewers stuck with it.

It wasn’t just the recipe that was changing. How Porter was aged evolved, too. Rather than age all their Porter for a medium length of time, brewers started to age just s proportion of it for a relatively long period and then blend this with “Mild“ or young Porter. This entailed brewing two types: Keeping Porter and Running Porter.

In the first seven decades of the 19th century London brewers produced two types of Porter for the domestic market:

- Running Porter which was sold young- Keeping Porter which was aged 6 to 12 months

The recipes for the two beers were essentially the same, except that the keeping version was much more heavily hopped as it would need to survive longer. The hopping rate was 50-100% greater than in the Running version. There might also be a higher proportion of roasted malts in the keeper.

Unlike like Pale Ale which was aged in trade casks – usually hogsheads – Keeping Porter was, as in the 18th century aged in enormous vats, holding thousands of barrels. The larger the volume of beer, the less that is in contact with oxygen.

During the ageing process Brettanomyces, which was either part of the pitching yeast or lurking in the oak staves of the vat, would slowly work away at any remaining fermentable material and produce vinous flavours, which were highly valued by drinkers, along with a certain degree of acidity.

Keeping Porter wasn’t usually sold straight, but blended with Running Porter in the brewery before being sent out to customers. The usual recommendation was to use no more than one third of Keeping Porter in the blend. This would add the aged flavour that was valued by customers without being too harsh or tart.

Keeping Porter was brewed in large quantities up until 1860, after which it quickly fell out of favour and by the end of the 1870’s had disappeared entirely. The public seems to have lost its love of the aged flavour. Though Porter remained extremely popular in London, it was all sold “mild”.

Some stronger Stouts were still aged, but as the quantities involved were much smaller, more modestly-sized vats were employed. London Porter brewers ripped out their large vats, vats which had once been a source of great pride.

Runners and Keepers in the 1850s

Year

Brewer

Beer

OG

FG

ABV

App. Atten-uation

lbs hops/ qtr

hops lb/brl

pale malt

brown malt

black malt

1856

Whitbread

P

1054.8

1013.0

5.53

76.26%

10.99

2.95

76.64%

19.46%

3.89%

1856

Whitbread

K

1057.1

1014.4

5.64

74.76%

15.42

3.85

75.83%

20.49%

3.69%

1855

Barclay Perkins

TT

1058.2

1018.0

5.31

69.06%

10.71

2.56

85.05%

11.63%

3.32%

1855

Barclay Perkins

Hhd

1057.6

1016.0

5.51

72.23%

15.17

3.70

83.30%

13.36%

3.34%

1855

Truman

Runner

1059.3

1017.2

5.57

71.03%

10.6

2.60

87.02%

9.87%

3.10%

1855

Truman

Keeper

1051.2

1016.1

4.65

68.65%

16.9

3.70

84.00%

12.80%

3.20%

Sources:

Whitbread brewing record held at the London Metropolitan archives, document number LMA/4453/D/09/050.

Barclay Perkins brewing record held at the London Metropolitan archives, document numberACC/2305/1/542.

Truman brewing record held at the London Metropolitan archives, document numberB/THB/C/057.

Porter in the free mash tun age

Not every brewer was keen to embrace the exhilarating freedom of a free mash tun. Whitbread continued on much as before. Though they did eventually submit to the temptation of sugar.

At least in their Porter. Because from the 1860s, sugar was popping up almost universally in Whitbread’s Stouts. It may seem odd that the cheapest beer was sugar-free. But that’s to misunderstand 19th-century brewing. Sugar was employed for specific purposes. Not as a way of lowering costs.

When sugar does appear in Whitbread’s Porter just after 1900, it doesn’t appear to be a deliberate choice. But simply a result of falling Porter sales. Which meant it was mostly brewed as part of a parti-gyle with Stout. The recipe of which already contained sugar. There was always only going to be one loser in a clash of recipes.

It was a sign of the fading fortunes of Porter before the war that it was rarely brewed single-gyle. In 1900, it was still very much the boss of the parti-gyle. And that it was becoming the junior partner in parti-gyles. The brews from 1902-1903 are about five barrels of Porter to one of Stout. But in 1907, there’s a parti-gyle with almost twice as much Stout as Porter.

The hopping rate, as measured per quarter, continued to drop. From around 8 lbs before 1900, to around 5lbs after 1910. Unless they were using hops with more alpha acid – which is unlikely as Whitbread mostly sourced their hops from Kent and had done for a long while – this change must have impacted the character of the beer.

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